Marcus Rashford is another doubt with illness - but there are suggestions the England striker could be a surprise inclusion against Chelsea.

But Mourinho has made it clear that securing Champions League football next season is a must - which means the Cup could prove too much of a distraction.

Mourinho will prioritise the Europa League

“For me it’s just a game that comes in the wrong moment for us,” said the United manager. “Because the Europa League is a competition that can give us a Champions League spot, and the FA Cup, it isn’t.

"So the Europa League is more important than the FA Cup for us."

Mourinho still hopes to secure a top four finish this season.

But despite a run of only one defeat in 28 games in all competitions they remain sixth in the Premier League - six points adrift of fourth placed Liverpool, albeit with two games in hand.

The mounting number of rearranged fixtures - including the Manchester derby - will make for a potentially hectic run-in, especially if United continue to fight on three fronts.

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Mourinho is increasingly wary of the advantage of top four rivals Liverpool and Arsenal, who are not involved in Europe.

“The boys are doing really well, but we have opponents in different circumstances to us,” he said. “Arsenal now are out of the Champion League, Chelsea without playing European competition, Liverpool not playing in European competition and we are in this run.

“We have Rostov on Thursday, then we have Middlesbrough on the Sunday at 12:15. It’s very difficult for the boys, but these are the boys.

“Even in a match where it is impossible to play, we don’t play, we fight.”